Protective effect of a water-soluble polysaccharide from Salvia miltiorrhiza Bunge on insulin resistance in rats

► Salvia miltiorrhiza has been used clinically and experimentally for treatment of diabetes mellitus. ► A water-soluble polysaccharide (SMPW1) was obtained from S. miltiorrhiza. ► Tert-butyl hydroperoxide (t-BHP) induced insulin resistance (IR) in rats, accompanied with oxidative stress. ► SMPW1 treatment had potent antioxidant activities to modeled rats. ► SMPW1 treatment improved IR in diabetic rats via reduction of oxidative stress.